A sailplane-ornithopter, which has two pairs of flapping wings, links, cables, interconnected rods, and loops is known (USSR patent no. 1205, 64 C 33/02). A man-powered flying device with two flapping wings, and two different variants of stands and arms pedals, and links is known (M. K. Tichonov Moscow. 1949, pp. 168).
A motorised ornithopter with flapping wings with feather-shaped panels, where a mechanism automatically controls the rotation of its rods to the necessary angle, is known (USSR, certificate of authorship no. 187 533). A flying apparatus with inclined horizontal wing axes, two flapping wings consisting of a wing panel with a solid part and a second part consisting of panels-flaps mounted on rotatable rods, is known (French patent no. 2 171 946). A serious deficiency of the flapping wings of these flying devices is their imperfect aerodynamic profiles: the movement of the rods during the wings' rising-upbeat cycle creates a negative aerodynamic force directed downward. Thus these apparatuses cannot fly at slow speeds.